backyard heat treating O1 steel

O

Owl Hollow11

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Mar 8, 2013
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i am new to knife making and wanted to post my results from heat treating. i made a small forge with fire brick. i use charcoal for my heat source, a 1inch steel pipe for the air inlet at the bottom. i use a blow dryer for the forced air. i recently heat treated 2 knives that i made out of O1 steel. 1/8" thick and OAL blade lenghts of 7 and 8 inches. one is a skinning knife and the other is a boning knife. the blades are 1 1/4" and 1 3/8" wide. quenching is canola oil that i warmed to 140 deg. f. i heated my forge for about 15 min. then put the blades in, blade down, and soaked for 15 min. they were non magnetic after about 4 min. i quenched in my canola oil, let them cool off enough to handle with plain leather gloves, then put them in my oven that was already preheated to 440 deg. i left them in there for 1 1/2 hours, took them out, let cool to room temp. and repeated the process.
i just had a labatory that i have acess to, do the rockwell hardness test. they were tested in a coulple of areas on the blade. they tested at 58.5.

i was wondering if i tempered at 400, would that give me a little higher rockwell number?
 
Yes, a lower temper would result in a little increase in hardness closer to 60RC assuming a proper hardening. I would, however, encourage you to test them thoroughly. Put handles on them and do some edge retention testing and chopping. When doing a 15 minute soak in a power-blown coal forge, it is very easy to over heat the steel and end up with significant grain growth, esepcially at the edge and tips. This will show itself in embrittlement and may be seen with edge chipping under use or even catastrophic failure of the blade.

--nathan
 
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